1. Field of the Invention
The present invention relates to a coloring apparatus for selectively coloring a copied image on a xerographic copy.
2. Related Background Art
A printing method called xerography has been conventionally well known. The printing method is a method where a photosensitive plate with electrostatic charge is exposed to form a latent image on it, the latent image is developed with toner to a visible image, the visible image is transferred to a sheet of paper and then the image is photographically fixed as a positive image. A method for giving coloring to a copied image of the xerographic copy (or picture) formed by the above mentioned method has been also proposed. Specifically, at first, a transfer sheet with a predetermined colored layer is superimposed on the formed xerographic copy. When it is heated, the toner on the xerographic copy is melted and the toner becomes tacky, as a result of which the layers including the colored layer of the transfer sheet remains on the copied image in a shape of the portion touching the copied image, after the transfer sheet is peeled off.
A transfer sheet and coloring apparatus to be used in the above mentioned method are disclosed in for example U.S. Pat. No. 4,006,267. The coloring apparatus is illustrated in FIG. 1. The coloring apparatus includes a pair of rollers 103 which presses a substrate 101 to be transferred on and a transfer sheet 102 together, while heating them.
As illustrated in FIG. 2, a toner 104, which forming a part of a copied image, is photographically fixed on the surface of the substrate 101. When, using the apparatus of FIG. 1, the substrate 101 and the transfer sheet 102 are pressed together while heated and then the transfer sheet 102 is peeled off, whereby a colored donor layer 107 at a portion in press-contact with the toner 104 is stripped off from the transfer sheet 102 including a metal film 105, so that the colored donor layers 107 are adhered on the toner 104 on the substrate 101. According to this function, it transfers a part of the colored donor layer 107 from the transfer sheet 102 to the toner 104 on the substrate 101. By the way, an individual sheet type of transfer sheet including a back sheet 106 is available as illustrated in FIG. 3 besides a roll shape type of the transfer sheet 102 as described in the above.
In the conventional apparatuses as described above, there is a problem that it is easy to transfer the colored donor layer to the entire copied image with the toner 104 on the substrate 101 but when the transfer is done only to a part of the copied image, a process for covering a predetermined part of the substrate 101 with a masking material is needed, resulting in complicated transferring operation.
There is another problem that, after the transfer sheet is cut into an appropriate size, it is ironed with a hot iron or the like, but at that time the iron may touch the other toner on the substrate 101, resulting in blotting of toner or adhering of toner to the iron. In addition to that, the apparatus is not easily carried resulting in restriction of a working place. A further drawback is that the toner at a portion to be transferred is not easily observed because the substrate is under the transfer sheet when transferring.